Support Technique of Giant Sector-shaped Segmented Mirror Telescope

Based on the segment mirror request of a giant telescope, comparing hexagonal segments with sector-shaped segment the difference is found. The finite element method was used to analyze the sector-segment mirror deformation under the gravity. The principal aim is to optimize the numbers of the support points and the array of the support. Three schemes, models with 18 points, 24 points and 27 points, are compared by calculating the mirror deformation under the gravity. After the calculation, the model with 27 points is the best one under which the mirror surface deformation is less than 10 nm, which meets the specification. Then, the mirror surface deformation was calculated under the gravity with the optimized axial support and the lateral support in the central diaphragm when the primary mirror points to three different directions:the horizontal, vertical and 45°. The calculation results show that all the shape changs in the sector-shaped submirror are less than 10 nm.